Scaling Properties of Azimuthal Anisotropy of Mesons and Baryons at RHIC

摘要

Detailed measurements of the azimuthal anisotropy (v_2) for identified charged particles are reported as a function of transverse momentum (p_T) and cen-trality for Au+Au collisions at (s_(NN))~(1/2) = 200 GeV. The measurements indicate clear evidence for eccentricity and particle flavor scaling over a broad range of centralities and transverse rapidity y_T, indicating a hydrodynamical origin of the fine structure of azimuthal anisotropy at RHIC. The observed scaling supports the picture of a suddenly hadronizing (recombining) fluid of quarks. An apparent breaking of flavor scaling at relatively large values of y_T points to an important change in the mechanism for particle emission.